Thermostatic control of turbine cooling air

Abstract

A gas turbine engine is provided with hollow guide vanes having thermally responsive actuators mounted within each for individually controlling the cooling air flow therethrough in response to local temperature variations.

What is claimed is: 
     
       1. A gas turbine engine guide nozzle, of the type having a plurality of hollow, air cooled vanes extending generally radially between annular inner and outer shroud rings, comprising: a plurality of air inlet orifices in one of said shroud rings, with one orifice adjacent the end of each of said plurality of vanes for admitting cooling air flow into the hollow interior thereof; and   a plurality of individually adjustable air control means for varying the flow of sad cooling air through each vane by variably blocking each of said orifices,   said air control means contained within the hollow interior or of each vane near the leading edge thereof and including a sealed convoluted cylinder, an expandable material in said cylinder, and a metering pin attached to one end of the cylinder and aligned with said inlet orifice.   
     
     
       2. The nozzle of claim 1 wherein said adjustable air control means are automatically adjusted in response to a selected engine parameter. 
     
     
       3. The nozzle of claim 2 wherein said selected engine parameter is the temperature of the adjacent vane and said air control means is thermally responsive thereto. 
     
     
       4. A gas turbine engine guide nozzle, of the type having a plurality of hollow, air cooled vanes extending generally radially between annular inner and outer shroud rings, comprising: a plurality of air inlet orifices in one of said shroud rings, with one orifice adjacent the end of each of said plurality of vanes for admitting cooling air flow into the hollow interior thereof; and   a plurality of individually adjustable air control means for varying the flow of said cooling air through each vane by variably blocking each of said orifices, said air control means being automatically adjusted in thermal response to the temperature of the adjacent vane,   said thermally responsive air control means being contained within the hollow interior of each vane near the leading edge thereof and includes a sealed convoluted cylinder, containing an expandable material, with a metering pin attached to one end and aligned with said inlet orifice.   
     
     
       5. The nozzle of claim 4 wherein said expandable material is sodium or lithium vapor. 
     
     
       6. The nozzle of claim 4 wherein said metering pin has a conical surface which cooperates with said inlet orifice to provide an air flow area which varies from a minimum amount at one temperature to a greater amount at a higher temperature. 
     
     
       7. An air cooled hollow vane for guiding hot gases within a gas turbine engine comprising: at least one air inlet orifice and one air exit hole in the walls of said hollow vane, and   an air control means for varying the flow area of said inlet orifice in response to the cooling needs of said vane,   said air control means including a tapered metering pin movable within said orifice and attached to a thermally responsive bellows.   
     
     
       8. The vane of claim 7 wherein said thermally responsive bellows includes a sealed convoluted cylinder containing a thermally expandable material. 
     
     
       9. The vane of claim 8 wherein said expandable material is selected from the group consisting of sodium, lithium and the like. 
     
     
       10. The vane of claim 7 wherein said bellows is located internally of the leading edge of said hollow vane. 
     
     
       11. A method of cooling a hollow guide vane in a gas turbine engine comprising the steps of: supplying cooling air to an orifice having a fixed cross-sectional flow area leading into said hollow guide vane,   variably blocking said flow area by interposing a movable metering pin adjacent said orifice, and   moving said metering pin with an attached thermally responsive actuator so that the amount of said cooling air flowing through said vane increases as the vane's temperature increases,   the step of moving said metering pin including expanding a sealed convoluted cylinder, attached to said pin, by increasing the vapor pressure of a material contained therein with heat transferred from said vane.   
     
     
       12. A method of cooling a hollow guide vane in a gas turbine engine comprising the steps of: supplying cooling air to an orifice having a fixed cross-sectional flow area leading into said hollow guide vane,   variably blocking said flow area by interposing a movable metering pin adjacent said orifice,   moving said metering pin with an attached thermally responsive actuator so that the amount of said cooling air flowing through said vane increases as the vane's temperature increases; and   flowing cooling air out of numerous small exit holes in the vane to form a film of cooling air adjacent the surfaces thereof.